Lange Otto L, Green T G Allan
Julius-von-Sachs-Institut für Biowissenschaften der Universität Würzburg, Lehrstuhl für Botanik II, Julius-von-Sachs-Platz 3, 97084 Würzburg, Germany.
Oecologia. 2005 Jan;142(1):11-9. doi: 10.1007/s00442-004-1697-x. Epub 2004 Aug 19.
Five species of lichens, the majority members of a soil-crust community ( Cladonia convoluta, Diploschistes muscorum, Fulgensia fulgens, Lecanora muralis, Squamarina lentigera) showed seasonal changes of temperature sensitivity of their dark respiration (DR) to such an extent that several substantially met the definition of full acclimation, i.e. near identical DR under different nocturnal temperature conditions during the course of the year. C. convoluta, for example, had maximal DR at 5 degrees C of -0.42, -1.11 and -0.09 nmol CO(2) g(-1) s(-1) in autumn, winter, and summer, respectively, a tenfold range. However, at the mean night temperatures for the same three seasons, 9.7 degrees C, 4.2 degrees C and 13.6 degrees C, maximal DR were almost identical at -1.11, -0.93, and -1.45 nmol CO(2) g(-1) s(-1). The information was extracted from measurements using automatic cuvettes that continuously recorded a sample lichen's gas exchange every 30 min under near-natural conditions. The longest period (for L. muralis) covered 15 months and 22,000 data sets whilst, for the other species studied, data blocks were available throughout the calendar year. The acclimation of DR means that maximal net carbon fixation rates remain substantially similar throughout the year and are not depressed by increased carbon loss by respiration in warmer seasons. This is especially important for lichens because of their normally high rate of DR compared to net photosynthesis. We suggest that lichens, especially soil-crust species, could be a suitable model for fungi generally, a group of organisms for which little is known about temperature acclimation because of the great difficulty in separating the organism from its growth medium. Fungi, whether saprophytic, symbiotic or parasitic, including soil lichens, are important components of soil ecosystems and contribute much of the respired CO(2) from these systems. Temperature acclimation by fungi would mean that expected increases in carbon losses caused by global climate warming from soil ecosystems might not be as extensive as first thought. This would ameliorate this positive feedback loop present in some climate models and might substantially lower the predicted warming.
五种地衣，即土壤结皮群落中的主要成员（卷枝石蕊、藓生双缘衣、灿烂黄衣、墙生茶渍衣、鳞叶石果衣），其暗呼吸（DR）的温度敏感性呈现季节性变化，以至于有几种地衣基本上符合完全驯化的定义，即在一年中不同夜间温度条件下，暗呼吸速率几乎相同。例如，卷枝石蕊在秋季、冬季和夏季的5摄氏度时，最大暗呼吸速率分别为-0.42、-1.11和-0.09 nmol CO₂ g⁻¹ s⁻¹，相差十倍。然而，在相同三个季节的平均夜间温度（分别为9.7摄氏度、4.2摄氏度和13.6摄氏度）下，最大暗呼吸速率几乎相同，分别为-1.11、-0.93和-1.45 nmol CO₂ g⁻¹ s⁻¹。这些信息是通过使用自动比色皿测量获得的，该比色皿在接近自然的条件下，每30分钟连续记录一次地衣样本的气体交换。最长的记录期（墙生茶渍衣）涵盖了15个月和22000个数据集，而对于其他研究的物种，全年都有数据块。暗呼吸的驯化意味着最大净碳固定率在全年基本保持相似，不会因温暖季节呼吸作用导致的碳损失增加而降低。这对地衣尤为重要，因为与净光合作用相比，它们的暗呼吸速率通常较高。我们认为地衣，尤其是土壤结皮物种，总体上可能是真菌的合适模型，由于将真菌与其生长介质分离存在很大困难，人们对这一类生物体的温度驯化知之甚少。真菌，无论是腐生、共生还是寄生的，包括土壤地衣，都是土壤生态系统的重要组成部分，并且贡献了这些系统中呼出的大部分二氧化碳。真菌的温度驯化意味着全球气候变暖导致土壤生态系统中碳损失预期增加的幅度可能不像最初想象的那么大。这将改善一些气候模型中存在的这种正反馈循环，并可能大幅降低预测的变暖程度。
